Composite materials combine and maintain two or more distinct phases to produce a material that has properties far superior than either of its base materials[1] . “Polymers are the chemist’s contribution to the materials world[2] .” Typically made from crude oil, polymers and composites have been labeled with having a detrimental impact to the environment. Polymers and composites are currently the most commonly used material in the United States [3] . As their popularity increases, so also the awareness should increase for making these materials sustainable for the future. Polymer composites are being promoted as the materials of the 21st century because of their superior corrosion resistance, excellent thermal-mechanical properties, and their strength to weight ratio[4] . Although the effects of polymer and composite use may not be detrimental in our lifetime, the long-term effects on the environment should be seriously considered. “At the global scale we are consuming about 150% of the resource [sic] that the earth can renew in one year[5] . ” “A sustainable polymer is a plastic material that addresses the needs of consumers without damaging our environment, health, and economy[6] .”
According to the Environmental Protection Agency “sustainability creates and maintains the conditions under which humans and nature can exist in productive harmony, that permit fulfilling the social, economic and other requirements of present and future generations[8] .” In other words “sustainability … is meeting the needs of the present without compromising the ability of future generations to meet their needs[9] .” There are many alternatives to crude oil that make the production of polymers and composites not detrimental to the environment. These alternatives are, polymer feed stocks that can be synthesized from agricultural products (notably starch and sugar, via methanol and ethanol)[10] . Some thermoplastics are suitable for making composites[11]
Polymers are extremely large, and long chains of molecules that have similar bonds[13] . Polymers can be naturally occurring or synthetic. Natural polymers include DNA, RNA, spider silk, etc [14] . Some of the first synthetic polymers include Bakelite (1909), Rayon (1910), and Nylon (1935). Common uses for polymers are plastics, synthetic clothing, and computer hardware[15] .
A composite is made by combining two or more materials; generally these materials have different properties. These two materials provide unique characteristics, but they do not blend together and are therefore easy to distinguish apart[16] . One commonly used composites in civil engineering include Fiber-Reinforced Polymers (FRP). FRP's are desirable in structural applications where a high strength to weight or high stiffness to weight ratio is require [17] .
The Problem With Polymers
As mentioned in the above video, polymers, more specifically plastics, have become the most common type of material. The current manufacturing processes are not sustainable for two main reasons:
Cost Efficiency
Dependance on Fossil Fuels
Disposal
As shown in the figure below, fossil fuels and petroleum play a significant role in traditional polymers. Currently fossil fuels and petroleum are increasing in price. Many man-made polymers use petroleum or fossil fuels. These are limited resources, which have a rapidly decreasing life span and will eventually run out. Over the last 30 years the price of petroleum has increased by 150%. The final problem with traditional polymers, particularly plastics, has to do with their disposal. The very properties that make plastics desirable make them difficult to dispose properly. Plastics are cheap and durable. Durability means that they cannot be broken down or destroyed easily; therefore, they simply collect in landfills. How inexpensive plastics currently are means that they will be building up in those landfills very quickly[18].
Here is a visual representation for traditional polymers. Click on the picture for more information.
One group that is working intently on the sustainability of polymers is the University of Minnesota and their Center of Sustainable Polymers. Some of the biggest steps that they are taking include comparing several attributes of complete natural fibers, composites of partial natural fibers mixed with traditional materials, and entirely traditional materials. Several characteristics are being tested, including compression strength, thermal conductivity, and the effects of aging materials on each of the properties. These test have come up with varying results. For example, in the polyurethane flexible foam tests, 30% natural soybean fibers yields the most substantial increase in strength[20] . While at the same time the thermal conductivity was increased more with aging in the natural soy-based foams[21] . The only types of natural fibers that are currently used commercially are those of starches, corn, sugarcane, seed oils, soybean, and other vegetable oils . However, scientists are currently working on using agricultural waste products such as corn sheaths[22] .
Major events in the history of polymers, from their first believed use to beginning of mass production
“Composite materials have been used in construction for thousands of years. Straw has been used to reinforce bricks for over 2000 years and this method is still used today[24] .” Looking back to ancient Greece there is evidence of metal reinforcements used in concrete beams dating back two 1000 years ago[25] .” Organic polymers such as cellulose and rubber are naturally occurring substances that have been forming since creation. As shown in the above flow chart, the first known use of these substances occurred in the 1500’s when the Mayan’s used rubber. It was believed that molecules over 1000 atomic mass units (amu’s) were impossible to form until the early 1900’s when Dr. Polanyi examined cellulose more closely. From there, man-made polymers have been growing in popularity and uses. In the 1970’s polymers became the most widely used material. Today more polymers are used than steel, aluminum, and copper combined[26] . The idea and implementation of sustainability in polymers is “relatively new to the consumer market[27] .”
Until the late 1990s and early 2000s, composites were not a popular choice of material for construction and infrastructure applications. By the mid 2000s, composites had received their validity for high strength and rigid applications. Richard P. Wool has been one of many bimolecular engineers who have been working on making polymers more sustainable. His work has received five patents since 1992. Wool’s bio-based composite formula started mass production in Dixie Chemicals resins for a worldwide market in 2012[28] . In 1999, the construction sector was the world’s second largest consumer of polymer composites representing 35% of the global market[29] . Polymers are now used in almost limitless applications with their potential only to increase in the future.
The major event in the wide spread growth of man made polymers.
As previously mentioned, polymers come in hundreds of different types, from rubbers to plastics to insulating foams. These polymers have consistent properties that are well known and understood. The ingredients that go into the production of these materials are not considered to be sustainable since they require the use of resources that are ever depleting. The greatest limitation of any natural sustainable polymer composite is attaining similar properties while maintaining a competitive cost. The natural materials that are used in the composites would delineate different types of sustainable polymers. Currently vegetable oils and starches are being added to make natural composite polymers. However, one of the problems with alternative is that it is not as sustainable as it could be since food sources are being used to make these polymers. One alternative that has clear advantages is the use of leaves and stalks. The main disadvantage with these is that they are currently still in preliminary testing[31] .
There are many advantages and disadvantages to different types of polymers and composites below are a few of the different variations of polymers and their properties.
Acrylonitrile butadiene styrene (ABS) is tough, resilient, and easily molded. Typically having a clear transparency, it can be easily colored to obtain different finishes.
Price (USD/kg): $2.40-2.60
Young’s Modulus (GPa): 1.1-2.9
Yield Strength (MPa): 18.5-51
CO2 Footprint (kg/kg): 3.6-4.0
Polyamides (Nylons) can be drawn into fibers that are as fine as silk and is many times used as a substitute. Applications can be used in rope to reinforced rubbers.
Price (USD/kg): $3.90-$4.30
Young’s Modulus (GPa): 2.62-3.2
Yield Strength (MPa): 50-94.8
CO2 Footprint (kg/kg): 7.6-8.3
Polypropylene (PP) is a very similar material as polyethylene in that it has similar price, processing methods and application. Being produced in large quantities and growing at about 10% per year, this polymer is being used in fire prevention applications if it receives a fire retardant.
Price (USD/kg): $1.85-$2.05
Young’s Modulus (GPa): 0.9-1.55
Yield Strength (MPa): 21-37
CO2 Footprint (kg/kg): 2.9-3.2
Epoxies are polymers that are thermosetting, having excellent adhesive properties. They are typically used for high strength bonding materials that are not similar in composition.
Price (USD/kg): $8.00-$10.00
Young’s Modulus (GPa): 2.35-3.08
Yield Strength (MPa): 36-71.7
CO2 Footprint (kg/kg): 6.8-7.5
Rubber (NR) is a rubber with which many people are familiar, finding this material in rubber raincoats. This is the most widely polymer that is produced worldwide at about 50%.
Price (USD/kg): $3.60-$4.90
Young’s Modulus (GPa): 0.0015-0.0025
Yield Strength (MPa): 20-30
CO2 Footprint (kg/kg): 2.0-2.2
Polylactic Acid (PLA) is a relatively new polymer that has been formulated from biodegradable polyesters. The organic ingredients in this polymer are corn, maize, or milk.
Construction Applications for Sustainable Polymers
According to Sebastian-George Maxineasa and Nicolea Taranu the best way to measure sustainability in construction is a Life Cycle Assessment (LCA). A LCA measures “environmental aspects and potential environmental impacts throughout a products life cycle from raw material acquisition through production, use, end-of-life treatment, recycling, and final disposal.” (LCA). Maxineasa and Taranu mention in their study about traditional building materials and fiber reinforced polymers that all building techniques have some level of negative impact on their environment. However, the use of different polymers (fiber reinforced polymers, glass fibers, carbon fibers, epoxies, and resins) can increase the sustainability of buildings and construction techniques. If traditional polymers and polymer manufacturing techniques can increase construction sustainability, and in general polymers can have increased sustainability through the use of natural fibers, then the use of natural fiber composites in construction techniques can make world of difference[34] .
Examples of Sustainable Polymers in Use
Although not a widely used option and still in its infancy, polyurethane foam composites are a very plausible option for application. These composites mix polyurethane polymers with the natural fibers in soybean oil polyol. According to a study done by the Center for Sustainable Polymers several years ago, the data on these composites is extremely comparable to that of traditional polyurethane foams[35] . These foams are generally used for their insulation properties. Polyurethane foams are applied in buildings and houses to shield them from the heat and cold of the elements[36] . Soybean and polyurethane composites proved to be comparable to traditional polyurethane polymers in many fields and exceeded them in a handful of others[37] . In the construction world, polymers are used to expedite processes that would take longer time if composites were not used. An example is thatof rapid deployment of bridge decks and highway structures[38] . A premade cast of a bridge deck is designed to be quickly set in place, ready to have concrete poured onto it. Reinforced polymers can be used in making concrete roads[39] . Polymer would be set in place allowing the concrete to bind to it and produce a stronger more durable product than that without a reinforcement polymer.
Bridge Deck Panel
Carbon Fiber structural members
Composite members replacing wood in home construction
Financial Considerations
Composites and polymers are typically viewed as an expensive material due to the fact that the initial material costs can be up to three times more than that of wood or steel. However, when considering cost you have to factor in long-term and short-term prices. Short-term costs can include construction, installation, and design. Long-term costs can include maintenance, modification, deconstruction, and disposal[40] .
when accounting for the costs of a material's entire life cycle, composites can cost up to 17% than its competitors. Composites last longer, require less maintenance, and are cheaper to dispose of, which contribute to a lower life cycle cost.
Current Research
Research is currently being done in the field of composites and polymers to improve properties, applying them in different ways, and confirming that they are environmentally friendly.
Certain composite materials are not bio-degradable. Therefore, to increase sustainability, research is being done to make composite materials more easily recycled. Imperial College-London is researching this topic for using recycled composites for structural applications [41] .
Applying sustainable polymers in a real world applications shows that it is less expensive, easier to handle, and requires less energy to make. The use of these new polymers in construction would reduce cost, ecological waste and time to produce the polymers[42] .
Scientists have developed a new polymer that has the properties that can extract mercury from soil, rivers and ponds. To create a clean environment the chemists made a block of polymer composites that turn yellow when they bind with mercury[43] . More information can be obtained at: http://phys.org/news/2015-10-colour-change-polymer-sustainable-solution-mercury.html
[45][46]
New research has been conducted to find how to create shape memory polymers. These Polymers can return to their original shape if the correct stimulus is applied to the polymer[47] . More information can be obtained at: http://www.azom.com/article.aspx?ArticleID=6038
^ Hota, G., Liang, R. (2011). Advanced Fiber Reinforced Polymer Composites for Sustainable Civil Infrastructures, Constructed Facilities Center, West Virginia.
^ Maxineasa, S., and Taranu, N. (2013). “Traditional Building Materials And Fibre Reinforced Polymer Composites. A Sustainability Approach In Construction Sector.” Bulletin Of the Polytechnic Institute Of Iasi- Construction & Architecture Section, 63(2), 55-68.
^ Maxineasa, S., and Taranu, N. (2013). “Traditional Building Materials And Fibre Reinforced Polymer Composites. A Sustainability Approach In Construction Sector.” Bulletin Of the Polytechnic Institute Of Iasi- Construction & Architecture Section, 63(2), 55-68.
^ Hota, G., Liang, R. (2011). Advanced Fiber Reinforced Polymer Composites for Sustainable Civil Infrastructures, Constructed Facilities Center, West Virginia.
^ Hota, G., Liang, R. (2011). Advanced Fiber Reinforced Polymer Composites for Sustainable Civil Infrastructures, Constructed Facilities Center, West Virginia.
^ Griffith, M. (2006). "Earthquake Protection of Masonry Buildings Using Fibre Reinforced Polymer Strengthening." University of Newcastle, <www.newcastle.edu.au>
^ Hota, G., Liang, R. (2011). Advanced Fiber Reinforced Polymer Composites for Sustainable Civil Infrastructures, Constructed Facilities Center, West Virginia.
^ Hota, G., Liang, R. (2011). Advanced Fiber Reinforced Polymer Composites for Sustainable Civil Infrastructures, Constructed Facilities Center, West Virginia.
^ Selamat, M. (2014). "Effect of Bamboo Fibre Length on the Mechanical Properties of Bamboo Fibre/Polypropylene Composite." Universiti Teknikal Malaysia Melaka, <ocs.utem.edu.my>
^ GangaRao, H. and Liang, R. (2006). "Applications of Fiber Reinforced Polymer Composites." West Virginia University, <www2.cemr.wvu.edu>
Introduction
Composite materials combine and maintain two or more distinct phases to produce a material that has properties far superior than either of its base materials[1] . “Polymers are the chemist’s contribution to the materials world[2] .” Typically made from crude oil, polymers and composites have been labeled with having a detrimental impact to the environment. Polymers and composites are currently the most commonly used material in the United States [3] . As their popularity increases, so also the awareness should increase for making these materials sustainable for the future. Polymer composites are being promoted as the materials of the 21st century because of their superior corrosion resistance, excellent thermal-mechanical properties, and their strength to weight ratio[4] . Although the effects of polymer and composite use may not be detrimental in our lifetime, the long-term effects on the environment should be seriously considered. “At the global scale we are consuming about 150% of the resource [sic] that the earth can renew in one year[5] . ” “A sustainable polymer is a plastic material that addresses the needs of consumers without damaging our environment, health, and economy[6] .”Table of Contents
[7]
Sustainability
According to the Environmental Protection Agency “sustainability creates and maintains the conditions under which humans and nature can exist in productive harmony, that permit fulfilling the social, economic and other requirements of present and future generations[8] .” In other words “sustainability … is meeting the needs of the present without compromising the ability of future generations to meet their needs[9] .” There are many alternatives to crude oil that make the production of polymers and composites not detrimental to the environment. These alternatives are, polymer feed stocks that can be synthesized from agricultural products (notably starch and sugar, via methanol and ethanol)[10] . Some thermoplastics are suitable for making composites[11][12]
Polymers and Composites
Polymers are extremely large, and long chains of molecules that have similar bonds[13] . Polymers can be naturally occurring or synthetic. Natural polymers include DNA, RNA, spider silk, etc [14] . Some of the first synthetic polymers include Bakelite (1909), Rayon (1910), and Nylon (1935). Common uses for polymers are plastics, synthetic clothing, and computer hardware[15] .A composite is made by combining two or more materials; generally these materials have different properties. These two materials provide unique characteristics, but they do not blend together and are therefore easy to distinguish apart[16] . One commonly used composites in civil engineering include Fiber-Reinforced Polymers (FRP). FRP's are desirable in structural applications where a high strength to weight or high stiffness to weight ratio is require [17] .
The Problem With Polymers
As mentioned in the above video, polymers, more specifically plastics, have become the most common type of material. The current manufacturing processes are not sustainable for two main reasons:- Cost Efficiency
- Dependance on Fossil Fuels
- Disposal
As shown in the figure below, fossil fuels and petroleum play a significant role in traditional polymers. Currently fossil fuels and petroleum are increasing in price. Many man-made polymers use petroleum or fossil fuels. These are limited resources, which have a rapidly decreasing life span and will eventually run out. Over the last 30 years the price of petroleum has increased by 150%. The final problem with traditional polymers, particularly plastics, has to do with their disposal. The very properties that make plastics desirable make them difficult to dispose properly. Plastics are cheap and durable. Durability means that they cannot be broken down or destroyed easily; therefore, they simply collect in landfills. How inexpensive plastics currently are means that they will be building up in those landfills very quickly[18] .Intended Improvements in Sustainability
One group that is working intently on the sustainability of polymers is the University of Minnesota and their Center of Sustainable Polymers. Some of the biggest steps that they are taking include comparing several attributes of complete natural fibers, composites of partial natural fibers mixed with traditional materials, and entirely traditional materials. Several characteristics are being tested, including compression strength, thermal conductivity, and the effects of aging materials on each of the properties. These test have come up with varying results. For example, in the polyurethane flexible foam tests, 30% natural soybean fibers yields the most substantial increase in strength[20] . While at the same time the thermal conductivity was increased more with aging in the natural soy-based foams[21] . The only types of natural fibers that are currently used commercially are those of starches, corn, sugarcane, seed oils, soybean, and other vegetable oils . However, scientists are currently working on using agricultural waste products such as corn sheaths[22] .History
“Composite materials have been used in construction for thousands of years. Straw has been used to reinforce bricks for over 2000 years and this method is still used today[24] .” Looking back to ancient Greece there is evidence of metal reinforcements used in concrete beams dating back two 1000 years ago[25] .” Organic polymers such as cellulose and rubber are naturally occurring substances that have been forming since creation. As shown in the above flow chart, the first known use of these substances occurred in the 1500’s when the Mayan’s used rubber. It was believed that molecules over 1000 atomic mass units (amu’s) were impossible to form until the early 1900’s when Dr. Polanyi examined cellulose more closely. From there, man-made polymers have been growing in popularity and uses. In the 1970’s polymers became the most widely used material. Today more polymers are used than steel, aluminum, and copper combined[26] . The idea and implementation of sustainability in polymers is “relatively new to the consumer market[27] .”Until the late 1990s and early 2000s, composites were not a popular choice of material for construction and infrastructure applications. By the mid 2000s, composites had received their validity for high strength and rigid applications. Richard P. Wool has been one of many bimolecular engineers who have been working on making polymers more sustainable. His work has received five patents since 1992. Wool’s bio-based composite formula started mass production in Dixie Chemicals resins for a worldwide market in 2012[28] . In 1999, the construction sector was the world’s second largest consumer of polymer composites representing 35% of the global market[29] . Polymers are now used in almost limitless applications with their potential only to increase in the future.
Variations of Polymer
As previously mentioned, polymers come in hundreds of different types, from rubbers to plastics to insulating foams. These polymers have consistent properties that are well known and understood. The ingredients that go into the production of these materials are not considered to be sustainable since they require the use of resources that are ever depleting. The greatest limitation of any natural sustainable polymer composite is attaining similar properties while maintaining a competitive cost. The natural materials that are used in the composites would delineate different types of sustainable polymers. Currently vegetable oils and starches are being added to make natural composite polymers. However, one of the problems with alternative is that it is not as sustainable as it could be since food sources are being used to make these polymers. One alternative that has clear advantages is the use of leaves and stalks. The main disadvantage with these is that they are currently still in preliminary testing[31] .There are many advantages and disadvantages to different types of polymers and composites below are a few of the different variations of polymers and their properties.
Acrylonitrile butadiene styrene (ABS) is tough, resilient, and easily molded. Typically having a clear transparency, it can be easily colored to obtain different finishes.
- Price (USD/kg): $2.40-2.60
- Young’s Modulus (GPa): 1.1-2.9
- Yield Strength (MPa): 18.5-51
- CO2 Footprint (kg/kg): 3.6-4.0
Polyamides (Nylons) can be drawn into fibers that are as fine as silk and is many times used as a substitute. Applications can be used in rope to reinforced rubbers.- Price (USD/kg): $3.90-$4.30
- Young’s Modulus (GPa): 2.62-3.2
- Yield Strength (MPa): 50-94.8
- CO2 Footprint (kg/kg): 7.6-8.3
Polypropylene (PP) is a very similar material as polyethylene in that it has similar price, processing methods and application. Being produced in large quantities and growing at about 10% per year, this polymer is being used in fire prevention applications if it receives a fire retardant.- Price (USD/kg): $1.85-$2.05
- Young’s Modulus (GPa): 0.9-1.55
- Yield Strength (MPa): 21-37
- CO2 Footprint (kg/kg): 2.9-3.2
Epoxies are polymers that are thermosetting, having excellent adhesive properties. They are typically used for high strength bonding materials that are not similar in composition.- Price (USD/kg): $8.00-$10.00
- Young’s Modulus (GPa): 2.35-3.08
- Yield Strength (MPa): 36-71.7
- CO2 Footprint (kg/kg): 6.8-7.5
Rubber (NR) is a rubber with which many people are familiar, finding this material in rubber raincoats. This is the most widely polymer that is produced worldwide at about 50%.- Price (USD/kg): $3.60-$4.90
- Young’s Modulus (GPa): 0.0015-0.0025
- Yield Strength (MPa): 20-30
- CO2 Footprint (kg/kg): 2.0-2.2
Polylactic Acid (PLA) is a relatively new polymer that has been formulated from biodegradable polyesters. The organic ingredients in this polymer are corn, maize, or milk.- Price (USD/kg): $2.40-$3.00
- Young’s Modulus (GPa): 3.45-3.83
- Yield Strength (MPa): 48-60
- CO2 Footprint (kg/kg): 3.4-3.8
All above data was taken from [32]Construction Applications for Sustainable Polymers
According to Sebastian-George Maxineasa and Nicolea Taranu the best way to measure sustainability in construction is a Life Cycle Assessment (LCA). A LCA measures “environmental aspects and potential environmental impacts throughout a products life cycle from raw material acquisition through production, use, end-of-life treatment, recycling, and final disposal.” (LCA). Maxineasa and Taranu mention in their study about traditional building materials and fiber reinforced polymers that all building techniques have some level of negative impact on their environment. However, the use of different polymers (fiber reinforced polymers, glass fibers, carbon fibers, epoxies, and resins) can increase the sustainability of buildings and construction techniques. If traditional polymers and polymer manufacturing techniques can increase construction sustainability, and in general polymers can have increased sustainability through the use of natural fibers, then the use of natural fiber composites in construction techniques can make world of difference[34] .Examples of Sustainable Polymers in Use
Although not a widely used option and still in its infancy, polyurethane foam composites are a very plausible option for application. These composites mix polyurethane polymers with the natural fibers in soybean oil polyol. According to a study done by the Center for Sustainable Polymers several years ago, the data on these composites is extremely comparable to that of traditional polyurethane foams[35] . These foams are generally used for their insulation properties. Polyurethane foams are applied in buildings and houses to shield them from the heat and cold of the elements[36] . Soybean and polyurethane composites proved to be comparable to traditional polyurethane polymers in many fields and exceeded them in a handful of others[37] . In the construction world, polymers are used to expedite processes that would take longer time if composites were not used. An example is thatof rapid deployment of bridge decks and highway structures[38] . A premade cast of a bridge deck is designed to be quickly set in place, ready to have concrete poured onto it. Reinforced polymers can be used in making concrete roads[39] . Polymer would be set in place allowing the concrete to bind to it and produce a stronger more durable product than that without a reinforcement polymer.Financial Considerations
Composites and polymers are typically viewed as an expensive material due to the fact that the initial material costs can be up to three times more than that of wood or steel. However, when considering cost you have to factor in long-term and short-term prices. Short-term costs can include construction, installation, and design. Long-term costs can include maintenance, modification, deconstruction, and disposal[40] .when accounting for the costs of a material's entire life cycle, composites can cost up to 17% than its competitors. Composites last longer, require less maintenance, and are cheaper to dispose of, which contribute to a lower life cycle cost.
Current Research
Research is currently being done in the field of composites and polymers to improve properties, applying them in different ways, and confirming that they are environmentally friendly.Certain composite materials are not bio-degradable. Therefore, to increase sustainability, research is being done to make composite materials more easily recycled. Imperial College-London is researching this topic for using recycled composites for structural applications [41] .
Applying sustainable polymers in a real world applications shows that it is less expensive, easier to handle, and requires less energy to make. The use of these new polymers in construction would reduce cost, ecological waste and time to produce the polymers[42] .
Scientists have developed a new polymer that has the properties that can extract mercury from soil, rivers and ponds. To create a clean environment the chemists made a block of polymer composites that turn yellow when they bind with mercury[43] . More information can be obtained at: http://phys.org/news/2015-10-colour-change-polymer-sustainable-solution-mercury.html
The University of Newcastle (Australia) is working on using FRP members to increase the earthquake protection in masonry buildings [44] .
More information can be obtained at:
http://www.newcastle.edu.au/research-and-innovation/centre/cipar/research/earthquake-protection-of-masonry-buildings-using-fibre-reinforced-polymer-strengthening
New research has been conducted to find how to create shape memory polymers. These Polymers can return to their original shape if the correct stimulus is applied to the polymer[47] . More information can be obtained at: http://www.azom.com/article.aspx?ArticleID=6038
Malaysian researchers are looking at how bamboo fibers can be incorporated into a biodegradable composite material for infrastructure
applications[48] . More information can be obtained at: http://ocs.utem.edu.my/index.php/mucet2014/MUCET2014/paper/viewFile/28/114
West Virginia University is researching the application of composites into civil and military infrastructure [49] .
More information can be obtained at: http://www2.cemr.wvu.edu/~rliang/liangandhota06.pdf
More Information
For more information on sustainable composite and polymer construction, please see: http://www.civil.ist.utl.pt/~cristina/
Brewer, J. “History of Polymers.” Materials Science and Technology Teachers Workshop, <http://matse1.matse.illinois.edu>.